So I've been reading all sorts of articles about whether electric cars really "pay off" or not.It's a topic of direct interest to me because I completely support the transition to electric cars, and I figure I will be buying some sort of vehicle in about a year or two, whenever my aging VW Cabrio finally gives up the ghost.And that's when I realized something about the often-cynical media coverage of this topic. Even though electric cars are useful almost exclusively as local, in-city commuter vehicles, a lot of analysts seem to prefer comparing electric cars to the highway mpg of a select few gas-powered cars. Such comparisons create a very false impression that a large percentage of gas vehicles actually exceed 40 mpg, when in fact only a few car models -- the newest most economical ones -- can claim "up to" 40 mpg on the highway.For me, the more accurate measure is to compare gas vs electric based on how I will use the car. And that means comparing electric cars against the CITY mpg of gas-powered vehicles. When you do that, the "pay off" numbers change -- a lot. Here was my test: My VW Cabrio spends very little time on the highway. My 14-mile round-trip commute to work occurs on city streets. My Saturday errands also occur on city streets, except for occassional forays into Northern Kentucky for cheap booze, movie night at the Levee, or across town to meet up with friends. In many social situations, we prefer to drive our other car -- a gas-sipping Hyundai Veloster, which Jackie uses for a highway-intense daily commute to suburban Mason. For sake of argument, I'm guessing that I put 10,000 miles a year on the Cabrio per year, maybe even less. Before electric cars became interesting, my first choice for replacing the Cabrio would have been a Mini Cooper convertible. (I'm still hoping they make an EV version, but so far, no luck). If I had to buy an all-electric car today, it probably would be the Ford Focus electric -- although the quirkiness of the Mitsubishi MiEV is kinda appealing.So. The Focus would cost me $31,700. The Mini convertible would cost $25,650. A difference of $6,050.The Mini gets 27 mpg city, which is decent for a gas car. In fact, very few gas powered cars can claim more than 30 mpg in the city. Several 2012 SUVs are as low as 16 and 17 mpg city. For the vast majority of gas-car drivers 40 mpg is an utter myth.Meanwhile, the Focus electric is rated at the equivalent of 110 mpg city -- that's more than FOUR times better mileage. It actually enjoys slightly higher city milege than its highway mileage (99 mpg) because, like most electric cars, the Focus uses the braking energy from stop-n-go driving to partially recharge the battery while traveling.So, the Mini convertible would require 370 gallons of gasoline to haul me 10,000 miles in a year. That's $1,480 at $4 gas. Or $1,850 at $5 gas. Based on the national average of 11 cents per kWh, the electric Focus will cost me about 3.8 cents a mile to drive. That's $380 a year -- or a savings of $1,100 a year at $4 gas; or $1,470 at $5 gas.So my "pay off" would happen in 5.5 years at $4 gas, or 4.1 years at $5 gas. After that, every year I keep the car (warranty lasting up to 100,000 miles) the savings on gas goes straight to my pocket. Expecting to keep an electric car for seven to 10 years is completely reasonable. That's what we've been doing with gas cars for quite some time. So for me, Mr. City Driver, the electric Focus clearly can work as a mid-priced choice. The little Mitsubishi would cost me even less -- just $21,300. At that price, there would be zero "pay off" issue to consider against a more-expensive Mini. Of course, neither vehicle is as cool as a Mini. It's also important to note that the pay-off gap for electric cars only gets smaller as time passes. Electric battery costs are down 30 percent since 2009. Newer tech is expected to drop battery costs even more. And $5 gas -- already a reality in some parts of the U.S. -- is very likely in the next decade.So I'm thinking, by 2013 or 2014, it will be very easy to choose a nice electric car and say goodbye to the gas station.